Holley Sniper install almost complete
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Drifting
Joined: Jul 2020
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From: San Diego
Holley Sniper install almost complete
Im installing a Holley Sniper efi on my 1968 with a 373 Stroker. I have an MSD tach drive distributor and the MSD cdi 6AL so the wiring seems a little funny to me. I went with the Holley in tank fuel pump so I didn't need a return line. I have side pipes so I pulled the passenger pipe off and welded in a O2 sensor bung just behind the collector.
The wiring is where it gets me. Ive read that I should not lock out my distributor until later to let it learn first. But I have a few questions:
1. Do I keep the vacuum advance connected to the carb vacuum or take it off and cap it?
2. It looks like the only wire that goes to the MSD box is the purple and green connector has one wire that runs to the gray on the MSD, correct?
3. Yellow doesnt connect to anything.
4. I believe I turned off the ‘rev limiter’ on the MSD but the only way to confirm this is if you turn it on and the tach does a tach sweep then its still turned on BUT I have the mechanical tach drive distributor so this wont work. Any other way to confirm it is off?
The wiring is where it gets me. Ive read that I should not lock out my distributor until later to let it learn first. But I have a few questions:
1. Do I keep the vacuum advance connected to the carb vacuum or take it off and cap it?
2. It looks like the only wire that goes to the MSD box is the purple and green connector has one wire that runs to the gray on the MSD, correct?
3. Yellow doesnt connect to anything.
4. I believe I turned off the ‘rev limiter’ on the MSD but the only way to confirm this is if you turn it on and the tach does a tach sweep then its still turned on BUT I have the mechanical tach drive distributor so this wont work. Any other way to confirm it is off?
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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- if you locked out the vacuum advance and EFI controls your timing you would cap the vacuum advance, other wise, you would still use it
- we emailed on this one..just read that the purple is the positve lead adn the green is negative....so connect to the purple ...page 4 of the msd instructions
- correct in your situation
- if you can see your msd box when you turn it on it should give you a blink code whether its on or off page 2
Thread Starter
Drifting
Joined: Jul 2020
Posts: 1,501
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From: San Diego
I started the car up last night and it seemed to run a little rough at first but then kind of smooth out. Everything seemed to be good. Im going to verify my timing to make sure its all set but I havent done anything with the distributor at this point and my vacuum advance is still connected to the vacuum port.
When the car ia running it makes about 60 pai of fuel preasure but when I turn it off it will drop over time. Is that normal or should pressure always remain? Ive checked for leaks and dont see any.
When the car ia running it makes about 60 pai of fuel preasure but when I turn it off it will drop over time. Is that normal or should pressure always remain? Ive checked for leaks and dont see any.
Drifting
Joined: Mar 2011
Posts: 1,347
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From: Kernersville NC
I started the car up last night and it seemed to run a little rough at first but then kind of smooth out. Everything seemed to be good. Im going to verify my timing to make sure its all set but I havent done anything with the distributor at this point and my vacuum advance is still connected to the vacuum port.
When the car ia running it makes about 60 pai of fuel preasure but when I turn it off it will drop over time. Is that normal or should pressure always remain? Ive checked for leaks and dont see any.
When the car ia running it makes about 60 pai of fuel preasure but when I turn it off it will drop over time. Is that normal or should pressure always remain? Ive checked for leaks and dont see any.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,209
Likes: 9,347
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Yes its normal as long as you dont see a puddle under the car, when you start it, turn the key to on, wait a few seconds to let the pump charge the fuel line, then crank it.
Race Director
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
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Cruise-In VIII Veteran
Should bump straight up to 58 - 60 PSI when key is turned to run. Fuel pump will run for 10 - 30 seconds to prime the line. then if engine hasn't started pump will stop running until ECM sees a tach signal. Then pump runs again.
A slight bleed off is normal. Should hold to at least 55 PSI for a couple minutes.
A slight bleed off is normal. Should hold to at least 55 PSI for a couple minutes.
